The carton with which we are concerned here has a so-called lock bottom which folds down into position when the carton walls are squared up. At the same time, a platform formed integrally with the carton walls folds down into place so that it is spaced above the carton bottom wall. Usually, openings are formed in the platform for receiving, retaining and isolating vials, bottles or other fragile articles contained in the carton. A carton of this general type is disclosed in U.S. Pat. No. 3,089,631 owned by the assignee of the present application.
As seen from that patent, the platform created in that prior carton comprises a single panel which spans the entire bottom wall and is unsupported other than at its edges. Accordingly, the platform tends to sag, with the result that the articles retained by the platform are not supported and isolated as well as they might be. Consequently, when that carton is handled roughly, the articles may smash against one another and break.
Also, in the prior carton construction, in order to lock the carton bottom wall and platform in place when the carton is set up, tab-receiving slots must be provided in one or more of the carton walls. Such slots provide access into the carton for dirt, moisture and insects, which can ruin the carton contents, particularly if the filled carton has a relatively long shelf-life.
Also, prior boxes of this type, typified by the one described in the aforesaid patent, are relatively expensive to make because of wastage of paperboard material due to the shape of the blank used to form the prior carton. For all of the aforesaid reasons, auto platform cartons generally have not seen as much use as might be desired.